1. Field of the Invention
The present invention relates to an electric working apparatus. More specifically, the present invention relates to an electric working apparatus which includes a movable body supplied with an electric power through a power supply cord and performs work such as transfer of components, cleaning and so on.
2. Description of the Prior Art
One example of such a kind of prior art is disclosed in Japanese Patent Application Laid-Open No. 62-268305, wherein a movable body is provided with a cord reel mechanism for winding a power supply cord which is connected to a plug socket provided on a wall.
In order to enlarge a working space of such a movable body, it is necessary to make a length of the power supply cord longer, and therefore, the cord reel mechanism becomes large.
In the above described prior art, since the cord reel mechanism is provided on the movable body, the movable body becomes large and a weight thereof is increased due to a large-sized cord reel mechanism, and this is not favorable in cost.
In general, a cord reel is driven by a motor to wind or unwind the power supply cord in the cord reel mechanism; however, if the cord reel is controlled only by on/off of the motor, a large change occurs in tension of the power supply cord between a timing when the motor is turned-on and a timing when the motor is turned-off. Therefore, it was impossible to smoothly and stably wind-up the power supply cord in the cord reel mechanism of the prior art.
In order to solve such a problem, a method wherein the tension of the power supply cord is kept at constant by using a hysterisis clutch, for example; however, a further problem occurs in generation of noise and durability because the motor is always driven in this method.
In addition, in the above described prior art, when the movable body moves, the power supply cord twines about the movable body so that the movement of the movable body and the work by a working mechanism may be prevented.